The Onset and Duration of Action of 0.2% Lidocaine in a One-per-Mil Tumescent Solution for Hand Surgery

BACKGROUND: One-per-mil tumescent solution, which contains 0.2% lidocaine with 1:1,000,000 epinephrine, has been reported to be clinically effective for hand surgery under local anesthesia. However, it was lacking in its basic pharmacokinetics profile in regard to the onset of action (OOA) and duration of action (DOA). METHODS: A randomized, double-blind study was conducted on 12 volunteers who met the inclusion criteria from October to November 2014. All volunteers had their right and left ring finger pulps injected with either one-per-mil solution or 2% lidocaine. Semmes-Weinstein and two-point discrimination tests were used to test sensation. Visual analogue scale was recorded at the time when the finger lost its sensation and when it regained normal sensation to measure the OOA and DOA. The data were then analyzed with a paired t-test and a Wilcoxon signed-rank test. RESULTS: The OOA and DOA of 2% plain lidocaine were 1 minute and 99.67 minutes, respectively. Meanwhile, 0.2% lidocaine in a one-per-mil tumescent solution showed an OOA of 5 minutes and a DOA of 186.83 minutes. The OOA of 0.2% lidocaine in a one-per-mil tumescent solution is statistically shorter than 2% plain lidocaine (P=0.04); while its DOA is statistically longer than 2% plain lidocaine (P<0.001). CONCLUSIONS: The 0.2% lidocaine in a one-per-mil tumescent solution is statistically and clinically superior to 2% plain lidocaine in achieving longer duration of local anesthesia.